big block vs tunnel hump... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**jocko** · 05-27-2012, 09:42 PM

Are all big block trucks big hump?

Are all 4x4s big hump?

Are all 2WD non-big block small hump?

Thanks!

Shyguy · 05-27-2012, 09:46 PM

Two wheel drives with either the SM-420 or SM-465 4 speed transmission have the high humps.

71swb4x4 · 05-27-2012, 10:05 PM

And maybe 2wd with the TH400?? I am not sure on that one.

I think there have been some big blocks on here with small humps, but it is generally accepted that all were supposed to be high humps.

All 4x4's were high humps.

Beat68CST · 05-27-2012, 10:55 PM

My 327 Turbo 400 truck has a small hump.

You can fit a 400 with a BBC under a small too.

**jocko** · 05-27-2012, 11:32 PM

71swb4x4 -i had the same wonder - i.e. if the hump was for the TH400 of for the BB itself. Apparently it's for the engine, but not sure why - since it will fit the bb/th400 combo under a small hump apparently. Interesting. I'll "bet" it was because of the th400, even though it fits. Can't imagine what the engine would have to do with the hump unless it somehow dragged the trans a little higher with it.

**too much stuff** · 05-28-2012, 12:55 AM

I had a big block cheyenne 3 on the tree with a low hump...
And all 4x4 should be high hump.

**special-K** · 05-28-2012, 09:04 AM

I've had small block/TH400 trucks with small hump. I've had big block/3spd trucks and don't recall how they were,but I believe they were small hump. I think it was about extra cooling/air space for the big block/TH400 more than fit.

**jocko** · 05-28-2012, 12:38 PM

very interesting. lookin at a truck with 402/th400 and didn't notice - but when checked the catalog for carpets later, noticed that all bb trucks would get a high hump carpet if order per the catalog (which of course doesn't mean they know what they're talking about). Bottom line, get the truck, see the hump, then order...

Thanks gents, very helpful!

manimal · 05-28-2012, 12:42 PM

I had a 1972 C20 with a big block/Th400 and small hump.

**too much stuff** · 05-28-2012, 01:07 PM

Quote:

Originally Posted by manimal

I had a 1972 C20 with a big block/Th400 and small hump.

Every 71-72 with a big block/400 combo i have seen was high hump. Was the truck original?

manimal · 05-28-2012, 01:24 PM

The spid said it came with a 402(400) and the TH400. and the vins matched.

71 super · 05-28-2012, 02:12 PM

I had a 69 that was a factory bb and th400 c20 that was a small hump, my 68 1/2 ton is th400 with low tunnel,my 1/2 ton 70 and 71 bb trucks are th400 and high humps.

ole dollor · 05-28-2012, 04:18 PM

i believe that the big hump was for the old four speed trans only, the shorter hump was for everything else...

**jocko** · 05-28-2012, 04:53 PM

I would have assumed the same - but for SOME reason - LMC lists their carpets for all 4x4s and big blocks as high hump. This has turned into a very interesting thread - plenty of proof out there from y'all that proves it really could come either way with a big block and/or a TH400. The 4-speed theory makes sense, but is also disproven by all the folks out there with original big blocks and th400s that have a big hump. Apparently, there's no rhyme or reason! Thanks for posting guys.

**special-K** · 05-28-2012, 05:12 PM

LMC is not a good reference. They should simply list the carpet for high hump or low hump like everyone else does.One more thing to prove they are not GM Truck guys. Through the years engines,transmissions,and cabs have been swapped. C-series bodies have been put on 4wd frames,too. Just go by what you have NOW.

*Fitz* · 05-29-2012, 06:42 PM

Quote:

Originally Posted by ole dollor

i believe that the big hump was for the old four speed trans only, the shorter hump was for everything else...

x2!

hugger6933 · 05-29-2012, 06:52 PM

My 68 GMC came with the high hump it has and alawys had a t400. I also belive it to be a big block truck but for now it is a small block. The owner before me had it since the late 69's and traded the 396 for a 350 to some kids that offered to do all the work in the late 80's and said he diid'nt need all that power

**special-K** · 05-29-2012, 08:29 PM

Quote:

Originally Posted by ole dollor

i believe that the big hump was for the old four speed trans only, the shorter hump was for everything else...

Quote:

Originally Posted by Fitz

x2!

Wrong. Anything with the 4spd did get a high hump,but not "only" 4spd trucks. 4wds with 3spd or TH350 also got the high hump. In other words,"all" 4wds got one.The reason we are having this discussion is to find the rhyme or reason to when the high hump was used with other 2wd applications such as BBC and/or TH400.

ole dollor · 05-29-2012, 09:21 PM

okadoke....sounds good to me....

JCD · 05-30-2012, 04:08 AM

Quote:

Originally Posted by ole dollor

i believe that the big hump was for the old four speed trans only, the shorter hump was for everything else...

That would mean all high humps would have a hole cut in them for the shifter..
Which is not the case..

J.

05-27-2012, 09:42 PM	#1
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,975	big block vs tunnel hump... Are all big block trucks big hump? Are all 4x4s big hump? Are all 2WD non-big block small hump? Thanks!

05-27-2012, 09:46 PM	#2
Shyguy Junior Member Join Date: Dec 2006 Location: Southeast Missouri Posts: 2,436	Re: big block vs tunnel hump... Two wheel drives with either the SM-420 or SM-465 4 speed transmission have the high humps. __________________ '67 Chevy C-20 short stepper - build complete, 454/SM-465. '75 C-30 Single Cab DRW-350 small block/NP-435. '77 GMC-6500 Dump Truck, 427 Tall Deck. '92 GMC K-3500 Duallie, 454/4L80E.

05-27-2012, 10:05 PM	#3
71swb4x4 Senior Member Join Date: Nov 2003 Location: Brookings, SD Posts: 10,497	Re: big block vs tunnel hump... And maybe 2wd with the TH400?? I am not sure on that one. I think there have been some big blocks on here with small humps, but it is generally accepted that all were supposed to be high humps. All 4x4's were high humps. __________________ Some people are like slinkies, they aren't good for anything, but you can't help but smile when you see one tumble down the stairs.

05-27-2012, 10:55 PM	#4
Beat68CST Registered User Join Date: Oct 2010 Location: Buckeye Arizona Posts: 470	Re: big block vs tunnel hump... My 327 Turbo 400 truck has a small hump. You can fit a 400 with a BBC under a small too.

05-27-2012, 11:32 PM	#5
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,975	Re: big block vs tunnel hump... 71swb4x4 -i had the same wonder - i.e. if the hump was for the TH400 of for the BB itself. Apparently it's for the engine, but not sure why - since it will fit the bb/th400 combo under a small hump apparently. Interesting. I'll "bet" it was because of the th400, even though it fits. Can't imagine what the engine would have to do with the hump unless it somehow dragged the trans a little higher with it.

05-28-2012, 12:55 AM	#6
too much stuff Roadtrip! Join Date: Feb 2003 Location: Grand Rapids MN Posts: 13,795	Re: big block vs tunnel hump... I had a big block cheyenne 3 on the tree with a low hump... And all 4x4 should be high hump. __________________ 67 gmc custom lwb dakota truck. Sold...And bought back 69 swb 4x4 project (in progress) 70 c-10 lwb texas truck 70 4x4/BB/bkts/posi/tach(retired) 70 swb (wifes) 70 jimmy camper 71 K-5 factory 2wd 71 cheyenne 4x4/tach/posi/ plow rig 71 Cheyenne20 BB, buckets, tach, tilt, 4 speed 72 jimmy CST wyoming rig 72 jimmy Colorado rig 72 lifted texas 4x4 3/4 ton burb 65 fury conv. 383/auto 65 chrysler 300 "L" 413 auto

05-28-2012, 09:04 AM	#7
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: big block vs tunnel hump... I've had small block/TH400 trucks with small hump. I've had big block/3spd trucks and don't recall how they were,but I believe they were small hump. I think it was about extra cooling/air space for the big block/TH400 more than fit. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

05-28-2012, 12:38 PM	#8
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,975	Re: big block vs tunnel hump... very interesting. lookin at a truck with 402/th400 and didn't notice - but when checked the catalog for carpets later, noticed that all bb trucks would get a high hump carpet if order per the catalog (which of course doesn't mean they know what they're talking about). Bottom line, get the truck, see the hump, then order... Thanks gents, very helpful!

05-28-2012, 12:42 PM	#9
manimal Registered User Join Date: Oct 2006 Location: Southern Kalifornia Posts: 3,066	Re: big block vs tunnel hump... I had a 1972 C20 with a big block/Th400 and small hump. __________________ ------------------------------------------------------ -Lance 2000 Chevy C2500, 5.7, 4L80e 1999 Suburban K2500, 7.4, 4L80e 1980 Camaro..son's car...PROJECT

05-28-2012, 01:24 PM	#11
manimal Registered User Join Date: Oct 2006 Location: Southern Kalifornia Posts: 3,066	Re: big block vs tunnel hump... The spid said it came with a 402(400) and the TH400. and the vins matched. __________________ ------------------------------------------------------ -Lance 2000 Chevy C2500, 5.7, 4L80e 1999 Suburban K2500, 7.4, 4L80e 1980 Camaro..son's car...PROJECT

05-28-2012, 02:12 PM	#12
71 super Registered User Join Date: Sep 2005 Location: Canton North carolina Posts: 3,080	Re: big block vs tunnel hump... I had a 69 that was a factory bb and th400 c20 that was a small hump, my 68 1/2 ton is th400 with low tunnel,my 1/2 ton 70 and 71 bb trucks are th400 and high humps. __________________ 67 blue step side- bb 68 gold and white swb cst anniversary 68 custom swb hot rod Ls swap 69 swb cst 6 cylinder/ overdrive 69 black/black cst bb swb 70 orange and white cst Canada built truck swb bb 71 black and white super swb bb 71 red and white super swb 72 green and white super swb 4x4 62 nova wagon 400 series Ls swapped 68 Camaro 327/4 speed- 1 owner, original paint 66 Volkswagen bettle 69 auto stick Volkswagen Beetle

05-28-2012, 04:18 PM	#13
ole dollor Registered User Join Date: May 2012 Location: Anton, Texas Posts: 2,364	Re: big block vs tunnel hump... i believe that the big hump was for the old four speed trans only, the shorter hump was for everything else...

05-28-2012, 04:53 PM	#14
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,975	Re: big block vs tunnel hump... I would have assumed the same - but for SOME reason - LMC lists their carpets for all 4x4s and big blocks as high hump. This has turned into a very interesting thread - plenty of proof out there from y'all that proves it really could come either way with a big block and/or a TH400. The 4-speed theory makes sense, but is also disproven by all the folks out there with original big blocks and th400s that have a big hump. Apparently, there's no rhyme or reason! Thanks for posting guys.

05-28-2012, 05:12 PM	#15
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: big block vs tunnel hump... LMC is not a good reference. They should simply list the carpet for high hump or low hump like everyone else does.One more thing to prove they are not GM Truck guys. Through the years engines,transmissions,and cabs have been swapped. C-series bodies have been put on 4wd frames,too. Just go by what you have NOW. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ Last edited by special-K; 05-30-2012 at 07:09 AM.

05-29-2012, 06:52 PM	#17
hugger6933 Registered User Join Date: Oct 2008 Location: Marianna Arkansas Posts: 7,280	Re: big block vs tunnel hump... My 68 GMC came with the high hump it has and alawys had a t400. I also belive it to be a big block truck but for now it is a small block. The owner before me had it since the late 69's and traded the 396 for a 350 to some kids that offered to do all the work in the late 80's and said he diid'nt need all that power



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05-29-2012, 09:21 PM	#19
ole dollor Registered User Join Date: May 2012 Location: Anton, Texas Posts: 2,364	Re: big block vs tunnel hump... okadoke....sounds good to me....

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